The CENSUS system is a set of computer programs which enables the storage and retrieval of a data base of information on cancer patients treated at the Baltimore Cancer Research Center. The conputer programs and the data base are accessed from remote terminals connected to a commercial time-sharing computer facility. Structured data input programs facilitate the addition of new information to the data base. A flexible retrieval program produces patient listings sorted by patient name, cancer diagnosis, attending physician, status, and/or research protocols. A medical secretary updates the data base daily and then retrieves a CENSUS report which lists all inpatients currently on the Medical Oncology outpatient service and all Medical Oncology clinic visits made that day. A general-purpose information management software library performs data base manipulations and retrievals which previously required the development of special-purpose computer programs. Several programs have been written to produce administrative and accounting tabulations of the data stored on the system. The system has been in operation since August of 1971 and the data base currently contains records for over 1000 cancer patients.